1. Field
The described technology relates generally to a mask. More particularly, the described technology relates generally to a mask assembly including a frame supporting a plurality of unit masks.
2. Description of the Related Art
Examples of a flat panel display include an organic light emitting display, a liquid crystal display, a plasma display panel, etc. In order to manufacture the organic light emitting display, an electrode having specific patterns, an organic emission layer, etc. should be formed. The method for forming the electrode and the organic emission layer, etc. can be applied to a deposition method using a mask assembly.
More specifically, the organic light emitting display includes pixels and each includes an organic light emitting diode. The pixels are a basic unit for displaying images. The pixels are on a substrate and arrayed in a matrix form. The organic light emitting diode has an anode, a first electrode and a cathode, and a second electrode sequentially formed. Organic emission layers are included between the anode and cathode. Each layer emits light (such as red, green, and blue, etc.) for each pixel. Organic materials forming the organic emission layer are very vulnerable to moisture and oxygen, etc, such that they should be thoroughly isolated from moisture during a process of forming the organic emission layer and after forming the organic emission layer. Therefore, it is difficult to perform patterning using a general photolithography process. As such, the organic emission layer and the second electrode, etc. are formed using a mask. The mask has a pattern opening part for penetrating deposition materials only through a portion corresponding to each pattern formed.
Recently there has been used a mask assembly including a frame including an opening part and a plurality of unit masks in a band shape whose both ends are fixed to the frame, corresponding to the opening part. The mask assembly in the related art is fixed to the frame by applying tensile force to the unit mask. Thus, the shape of the pattern opening part formed in the unit mask may be deformed due to tensile force applied to the unit mask.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the described technology and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.